Additive removal device and additive removal method using the same

Abstract

The present invention provides an additive removal device including a barrel providing an internal space and having a polymer inlet on one side and a polymer outlet on the other side, a screw provided in the internal space of the barrel and rotating on its axis, and a solvent outlet provided at the one end of the barrel, the barrel being located between the polymer inlet and the polymer outlet, and including a swelling solvent inlet adjacent to the polymer inlet and a shrinking solvent inlet adjacent to the polymer outlet.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0140595, filed on October 27, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an additive removal device for removing additives contained in polymers for recycling the polymers, and a method for removing additives using the same. [Background technology]

[0003] Recently, the use of polymeric materials such as resins and plastics has increased as resin materials with desired physical properties for various applications and purposes have been developed. Generally, resins and plastics require a great deal of energy, from crude oil extraction to production, and a large amount of carbon is emitted during the process. Furthermore, when the resin or plastic contained in the final product is discarded, environmental pollution and the associated social costs for disposal are incurred. Therefore, recycling discarded resins is essential from the perspectives of reducing energy consumption, carbon emissions, and preventing environmental pollution. Thus, post-consumer recycled (PCR) resins are made by recycling resins discarded after end-use by end consumers, and efforts are ongoing to obtain PCR resins with desired purity and physical properties.

[0004] Meanwhile, polyvinyl chloride (PVC) resin has rigid or flexible properties, excellent moldability, competitive price, and versatile utility, making it suitable for a variety of applications. However, PVC resin cannot be used alone; it is mixed with plasticizers to achieve various physical properties, such as imparting flexibility and improving processability.

[0005] However, phthalate plasticizers, which have been used as plasticizers in the past, are harmful to the environment and human body and are subject to strict regulations both in Korea and abroad. Therefore, in order to recycle polymers such as existing polyvinyl chloride resins containing such phthalate plasticizers, commercialization is difficult unless the phthalate plasticizers can be removed. Therefore, in order to recycle polymers containing phthalate plasticizers, attempts have recently been made to effectively remove the phthalate plasticizers remaining in the recovered polymers.

[0006] As part of this effort, in order to remove additives such as plasticizers from recovered polymers, the so-called dissolution recrystallization method has been mainly used, in which the recovered polymer is dissolved using a solvent and then recrystallized using an antisolvent. However, in this case, the amounts of solvent and antisolvent used for dissolution and recrystallization are excessively large, and the physical properties of the recycled polymer thus recovered are poor. Furthermore, the large amount of solvent required results in excessive costs for facilities and equipment.

[0007] Therefore, there is a need to develop an apparatus that can efficiently remove additives such as plasticizers contained in recovered polymers while minimizing the amount of solvent used, and a method for removing additives from polymers using the apparatus. Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to provide a continuous processing method capable of highly efficiently removing plasticizers contained in polymers for polymer recycling, in order to solve the problems mentioned in the Background of the Invention, and to provide an apparatus for removing additives from polymers optimized for this method. [Means for solving the problem]

[0009] According to one embodiment of the present invention, there is provided an additive removal device including: a barrel having an internal space and a polymer inlet on one side and a polymer outlet on the other side; an axially rotating screw disposed in the internal space of the barrel; and a solvent outlet disposed at the one end of the barrel, wherein the barrel is positioned between the polymer inlet and the polymer outlet, and includes a swelling solvent inlet adjacent to the polymer inlet and a shrinking solvent inlet adjacent to the polymer outlet.

[0010] The present invention also provides a method for removing an additive, including the steps of preparing an additive removal device, supplying a polymer containing an additive to the polymer inlet, supplying a swelling solvent and a shrinking solvent to the swelling solvent inlet and the shrinking solvent inlet, respectively, transporting the supplied polymer to a polymer outlet by axial rotation of the screw, swelling the polymer in a swelling zone from the polymer inlet to the swelling solvent inlet, and shrinking the polymer in a shrinking zone from the swelling solvent inlet to the shrinking solvent inlet. [Effects of the Invention]

[0011] The additive removal device of the present invention is capable of continuously extracting additives from polymers even with a small device size and a small amount of solvent used, and can also improve the efficiency of removing the additives.

[0012] Furthermore, the additive removal method of the present invention differs from the conventional dissolution-recrystallization method in that it does not dissolve the polymer recovered from waste resin in a solvent, but rather impregnates the polymer with a swelling solvent, allowing the additives inside the polymer to be selectively diffused and extracted, thereby making it possible to remove the additives from the polymer. This reduces the amount of solvent used and simplifies the required equipment, improving economy.

[0013] Next, when removing the swelling solvent from the polymer swollen by impregnation with the swelling solvent, the swollen polymer can be shrunk by applying a shrinking solvent to the swollen polymer, thereby efficiently reducing the amount of solvent in the polymer and the amount of additives remaining in the solvent. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a vertical cross-sectional view showing an additive removal device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The terms and words used in the description and claims of the present invention should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0016] To facilitate understanding of the present invention, the present invention will now be described in more detail with reference to FIG.

[0017] An additive removal device 1 according to one embodiment of the present invention includes a barrel 10 providing an internal space and having a polymer inlet 20 on one side and a polymer outlet 30 on the other side, a screw 70 disposed in the internal space of the barrel 10 and rotating around its axis, and a solvent outlet 60 disposed at the one end of the barrel 10. The barrel 10 is located between the polymer inlet 20 and the polymer outlet 30 and may include a swelling solvent inlet 40 adjacent to the polymer inlet and a shrinking solvent inlet 50 adjacent to the polymer outlet.

[0018] First, the polymer may be a polymer recovered from waste resin, obtained by pretreating the waste resin, and may be in a particulate form. Meanwhile, the waste resin may be recovered from various products or applications molded using resin or its composition, regardless of whether it is hard or soft. Furthermore, the recovered polymer may be a single polymer or a resin composition blended with other resins.

[0019] The pretreatment refers to a series of processes for converting waste resin into a polymer suitable for application to the additive removal device of the present invention. For example, the pretreatment may be a process of first washing the waste resin with a solvent such as water to remove relatively large foreign matter such as dust, drying the waste resin, and then pulverizing it into particles.

[0020] Specifically, the average particle size (D50) of the polymer may be 0.1 mm or more and 2 mm or less. As the average particle size of the recovered polymer becomes smaller, the impregnation rate of the impregnation solvent increases, and the removal rate of the additive increases. However, there is a drawback in that the processing time increases to produce a recovered polymer with a small average particle size.

[0021] The type of polymer suitable for application to the additive removal device according to one embodiment of the present invention is not particularly limited, but when the additive to be removed by the additive removal device is a plasticizer, the polymer may be polyvinyl chloride (PVC).

[0022] Meanwhile, additives such as plasticizers, fillers, flame retardants, stabilizers, bulking agents, viscosity reducers, colorants, and heat stabilizers may be used to impart desired physical properties to the resin during or after polymerization of the polymer, molding, or other manufacturing processes, and these additives remain in the resin produced by the additives. Therefore, the additives may also be contained in waste resin recovered from products for recycling.

[0023] The reason why the additives must be appropriately removed when producing a recycled polymer from a polymer recovered from the waste resin is as follows.

[0024] First, if an excessive amount of additives remain, it may be difficult to produce a recycled polymer with good physical properties. The additives may cause deterioration in physical properties such as deformation or deterioration in surface properties of the recycled polymer, or deterioration in color properties such as discoloration.

[0025] Second, some additives have recently been restricted in use due to their environmental and human toxicity. That is, due to regulations that did not exist at the time of product manufacture, it is becoming increasingly possible to produce recycled polymers by removing regulated additives from recovered polymers to a desired level or lower.

[0026] For the above reasons, the additives that need to be removed from the recovered polymer containing the additives may mainly be plasticizers. Specifically, the plasticizers may be phthalate-based plasticizers. More specifically, the phthalate-based plasticizers may be one or more of dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl terephthalate (DOTP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), di-(2-ethylhexyl) terephthalate (DEHTP), and butyl benzyl phthalate (BBP).

[0027] Meanwhile, the method for removing additives according to one embodiment of the present invention is different from the conventional method of dissolving the polymer itself using a solvent and then recrystallizing it, in that it selectively dissolves only the additive while maintaining the polymer morphology. Such conventional dissolution and recrystallization methods have the disadvantage that it is difficult to remove additives such as plasticizers that have good compatibility with the resin, and in particular, this method requires the use of an excessive amount of solvent (antisolvent), which increases not only the solvent cost but also the cost of purifying it, resulting in poor purification efficiency relative to cost.

[0028] Therefore, the additive removal method of the present invention first involves contacting an additive-containing polymer with a swelling solvent, impregnating the polymer with the swelling solvent to swell the polymer, and then diffusing the additive within the polymer with the swelling solvent, thereby removing the additive from the polymer. Next, the polymer impregnated with the swelling solvent is contacted with a shrinking solvent to shrink the polymer, thereby minimizing the solvent content within the polymer. That is, as the swollen polymer is shrunk by the shrinking solvent, the swelling solvent containing the additive inside is expelled to the outside of the polymer to the maximum extent possible, ultimately reducing the additive content within the polymer.

[0029] Here, the term "immersion" refers not only to washing away additives (plasticizers) present on the surface of the recovered polymer with an impregnation solvent, but also to the impregnation solvent penetrating into the interior of the recovered polymer by diffusion, thereby eluting the additives (plasticizers) therein.

[0030] Furthermore, the present invention provides an optimal additive removal device 1 that can continuously perform the additive removal method, can reduce the amount of swelling solvent and shrinking solvent used, thereby improving economy, and can improve the efficiency of removing additives, specifically plasticizers.

[0031] In view of this, the barrel 10 according to an embodiment of the present invention is a component constituting the main body of the additive removal device 1, and may be tubular, extending in the longitudinal direction and having an internal space. The barrel 10 may be made of a material that is not deformed by the solvent described below, and specifically, may be made of a metal material or a glass material.

[0032] The internal space is a space where the polymer supplied to the polymer inlet 20 is transported to the polymer outlet 30 by the screw 70, and where the solvents supplied to the swelling solvent inlet 40 and the shrinking solvent inlet 50 are transported by gravity. The internal space may also refer to a space where additives contained in the polymer are removed due to swelling and shrinkage of the polymer.

[0033] Specifically, the barrel 10 may have a polymer inlet 20 on one side and a polymer outlet 30 on the other side. The polymer may be a polymer containing an additive, and the additive may be removed from the polymer by sequentially contacting the polymer with a swelling solvent and a shrinking solvent, which will be described later, through the polymer inlet 20. The polymer from which the additive has been removed may be discharged through the polymer outlet 30.

[0034] Meanwhile, the additive remover 1 may include an axially rotating screw 70 installed in the interior space of the barrel 10, and a torque supplying device 80 may be provided at the other end of the barrel 10 to apply torque to the screw 70. Here, the other end may be an end of the barrel 10 adjacent to the polymer outlet 30.

[0035] The torque supplying device 80 supplies a driving force for axial rotation to the screw 70, and specifically may be a motor.

[0036] Specifically, the screw 70 includes a shaft 71 connected to a torque supplying device 80 to rotate about its axis, and a plate 72 fixed to the outer periphery of the shaft 71 and extending in a spiral shape along the length of the shaft 71. The torque applied by the torque supplying device 80 causes the plate 72 to rotate around the shaft 71 as a rotation axis. Thus, the polymer supplied to the polymer inlet 20 is loaded onto the plate 72 and can be continuously transported to the polymer outlet 30 by the axial rotation of the screw 70.

[0037] On the other hand, the supply flow rate (g / min) of the polymer supplied to the polymer inlet 20 is determined by the volume (cm ) of one pitch p of the screw. 3 ), bulk density of the supplied polymer (g / cm 3 ) and screw rotation speed (RPM, min -1) and specifically, the following general formula 1 can be satisfied.

[0038] [General formula 1] Volume of one pitch p of the screw (cm 3 )*bulk density of supplied polymer (g / cm 3 ) * Screw rotation speed (min -1 ) * 0.1 ≦ Polymer supply flow rate (g / min) ≦ Volume of 1 pitch p of the screw (cm 3 )*bulk density of supplied polymer (g / cm 3 ) * Screw rotation speed (min -1 )*0.5

[0039] Meanwhile, according to one embodiment of the present invention, the additive removal device 1 may be disposed such that an extension line of the rotation axis of the screw 70, specifically, an extension line of the shaft 71, is inclined with respect to the ground. That is, the surface height of the polymer outlet 30 may be disposed higher than the surface height of the polymer inlet 20. By making the length of the support supporting the polymer outlet 30 side longer than the length of the support supporting the polymer inlet 20 side, an inclination angle z between the extension line of the rotation axis of the screw 70 and the ground can be realized.

[0040] Meanwhile, the inclination angle z between the extension of the rotation axis of the screw 70 and the ground allows the swelling solvent and shrinking solvent introduced into the internal space of the barrel 10 to be transported to the solvent discharge part 60 by gravity, and prevents the introduced swelling solvent and shrinking solvent from flowing back to the polymer discharge port 30 and being lost.

[0041] Furthermore, by controlling the inclination angle z between the extension of the rotation axis of the screw 70 and the ground, it is possible to determine the time that the swelling solvent and the shrinking solvent remain in the device and the time that the solvents come into contact with the polymer, thereby enabling more efficient removal of additives from the polymer.

[0042] Specifically, the inclination angle z between the extension of the rotation axis of the screw 70 and the ground surface can be 5 to 30 degrees. The inclination angle z is also related to the flow rates of the swelling solvent and shrinking solvent supplied. If the inclination angle exceeds 30 degrees, the solvent supplied to the barrel 10 through the swelling solvent inlet 40 or shrinking solvent inlet 50 is discharged without being sufficiently retained within the barrel's internal space. That is, despite its ability to swell or shrink the polymer, it is discharged in an excessively short time, resulting in excessive solvent consumption and increased energy consumption in the purification process for solvent reuse. Conversely, if the inclination angle is less than 5 degrees, the solvent supplied to the barrel is likely to be discharged from the polymer outlet 30 and be wasted. Furthermore, the solvent adjacent to the solvent outlet, i.e., the solvent with concentrated additives, cannot be smoothly discharged from the solvent outlet, which can reduce the efficiency of removing additives from the polymer.

[0043] According to an embodiment of the present invention, a swelling solvent may be supplied to the swelling solvent inlet 40 and a shrinking solvent may be supplied to the shrinking solvent inlet 50 .

[0044] Furthermore, the internal space of the barrel 10 can be functionally divided into a swelling zone 100 from the polymer inlet 20 to the swelling solvent inlet 40 and a shrinkage zone from the swelling solvent inlet 40 to the shrinkage solvent inlet 50. Specifically, the swelling zone 100 refers to the region of the cross section of the barrel 10 from the cross section including the center of the polymer inlet 20 to the cross section including the center of the swelling solvent inlet 40, and the shrinkage zone 200 refers to the region of the cross section from the cross section including the center of the swelling solvent inlet 40 to the cross section including the center of the shrinkage solvent inlet 50.

[0045] First, the polymer containing additives supplied through the polymer inlet 20 passes through the swelling zone 100 and the shrinkage zone 200 in the process of being transported to the polymer outlet 30 by the axial rotation of the screw 70 .

[0046] The distance x from the polymer inlet 20 to the swelling solvent inlet 40 may be the length of the swelling zone 100, and the distance y from the swelling solvent inlet 40 to the shrinking solvent inlet 50 may be the length of the shrinking zone 200. The ratio x / y of the distance x from the polymer inlet 20 to the swelling solvent inlet 40 to the distance y from the swelling solvent inlet 40 to the shrinking solvent inlet 50 may be 0.1 to 60, specifically 1 to 30. If the ratio x / y is less than 0.1, the residence time of the polymer in the shrinking zone may be longer than necessary, which may reduce the economic efficiency of the process. If the ratio x / y is greater than 60, the residence time of the polymer in the shrinking zone may be shorter than necessary, which may make it difficult for the swollen polymer to be sufficiently shrunk.

[0047] Meanwhile, in the swelling zone 100, the polymer containing the additive comes into contact with the swelling solvent, and the swelling solvent impregnates the polymer, causing the polymer to swell while maintaining its inherent molecular structure. The additive contained in the polymer diffuses through the impregnating solvent and is eluted to the outside of the recovered polymer, thereby removing the additive from the polymer.

[0048] For efficient removal of additives from polymers, the selection of the swelling solvent used to swell the polymer is important. First, the swelling solvent must be rapidly and uniformly impregnated into the polymer particles, and the maximum amount of additive contained in the polymer must be eluted by the swelling solvent impregnated into the polymer. Therefore, the swelling solvent must be selected taking into account the type of polymer and the type of additive to be removed.

[0049] In view of this, when the additive is a phthalate-based plasticizer, the swelling solvent may be one or more of cyclohexanone, cyclopentanone, N,N-dimethylacetamide, tetrahydrofuran, pyridine, 3-pentanone, 2-pentanone, dimethylformamide, methyl ethyl ketone, dichloromethane, 4-methylpentan-2-one, nitrobenzene, 1,4-dioxane, 1,1,2,2-tetrachloroethane, acetone, ethyl acetate, chloroform, and dimethyl sulfoxide, specifically methyl ethyl ketone. These solvents are preferred because they not only easily impregnate the polymer but also have excellent ability to elute the additive, such as the phthalate-based plasticizer, from the polymer.

[0050] In this way, in order to sufficiently impregnate the swelling solvent into the polymer in the swelling zone 100 and smoothly elute the internal additive due to the swelling of the polymer, the supply flow rate (cm ) of the swelling solvent supplied to the swelling solvent inlet 40 is set to 100. 3 / min) can be determined by the supply flow rate of the polymer and the bulk density of the supplied polymer. Specifically, the following general formula 2 can be satisfied:

[0051] [General formula 2] Feed flow rate of the supplied polymer (g / min) / bulk density of the supplied polymer (g / cm 3 )*0.5≦swelling solvent supply flow rate (cm 3 / min) ≦ Supply flow rate of supplied polymer (g / min) / Bulk density of supplied polymer (g / cm 3 )*10

[0052] That is, the supply volume flow rate of the swelling solvent (cm 3 / min) / Volumetric flow rate of polymer (cm 3 When the supply volume flow rate (cm / min) of the swelling solvent is 0.5 or more, the polymer can be sufficiently swollen and the residual additives in the polymer can be smoothly removed. 3 / min) / Volumetric flow rate of polymer (cm 3When the reaction rate (%) is 10 or less, unnecessary solvent use can be reduced, and purification costs due to excessive solvent use can be reduced, thereby improving the economic efficiency of the process.

[0053] Meanwhile, the residence time of the polymer in the swelling zone 100 can satisfy the following general formula 3 in relation to a value expressed by the average particle size (D50, mm) of the polymer.

[0054] [General formula 3] Average particle size of polymer (mm) * 5 ≦ Residence time in swelling zone (min) ≦ Average particle size of polymer (mm) * 240

[0055] That is, if the polymer resides in the swelling zone 100 for a time longer than [a value expressed as the average particle size of the polymer*5], the swelling solvent can penetrate the interior of the polymer, allowing the additives to be sufficiently eluted. On the other hand, if the polymer resides for a time longer than [a value expressed as the average particle size of the polymer*240], the economic viability of the process may decrease. Specifically, if the screw rotation speed (RPM) is excessively reduced to increase the residence time, the yield of polymer from which the additives have been removed per unit time decreases, or if the length of the swelling zone 100 is increased to increase the residence time, the size of the apparatus may increase.

[0056] Meanwhile, a mixture of the swelling solvent and the shrinking solvent may exist in the swelling zone 100. That is, the shrinking solvent supplied to the shrinking solvent inlet 50 passes through the shrinking zone 200 and the swelling zone 100 and is discharged to the solvent outlet 60, so that both the swelling solvent and the shrinking solvent exist in the swelling zone 100.

[0057] If the amount of shrinking solvent is excessively large compared to the swelling solvent in the swelling zone 100, the swelling of the polymer by the swelling solvent and solvent impregnation may be reduced, so the flow rates of the swelling solvent and shrinking solvent in the swelling zone 100 must be controlled at an appropriate ratio. Meanwhile, since the respective flow rates of the swelling solvent and shrinking solvent in the swelling zone 100 are ultimately determined by the flow rate of the swelling solvent supplied to the swelling solvent inlet 40 and the flow rate of the shrinking solvent supplied to the shrinking solvent inlet 50, it is important to appropriately control the ratio of these flow rates in order to ensure smooth impregnation of the swelling solvent and swelling of the polymer.

[0058] In this regard, the ratio of the volumetric flow rate of the shrinking solvent supplied to the shrinking solvent inlet to the volumetric flow rate of the swelling solvent supplied to the swelling solvent inlet may be 30% to 300% by volume. If the volumetric flow rate of the shrinking solvent is less than 300% by volume of the swelling solvent, i.e., if the swelling solvent is present in the swelling zone 100 in an amount three times or more the shrinking solvent, the additive dissolution function of the swelling solvent due to polymer swelling may be reduced. Meanwhile, considering the function of the shrinking solvent in the shrinking zone 200 and the efficiency of removing additives from the polymer thereby, the volumetric flow rate of the shrinking solvent must be maintained at a predetermined level or higher. Therefore, if the ratio of the volumetric flow rate of the shrinking solvent to the volumetric flow rate of the swelling solvent is less than 30% by volume, the shrinking solvent may not be supplied sufficiently, making it difficult to smoothly achieve the polymer shrinking function in the shrinking zone.

[0059] Meanwhile, the polymer swollen with the swelling solvent may be transferred to the shrinkage zone 200 within the barrel 10. The swollen polymer in the shrinkage zone 200 may come into contact with the shrinkage solvent. Specifically, the polymer transferred from the swelling zone 100 to the shrinkage zone 200 is impregnated with the swelling solvent containing the dissolved additives. If the swollen polymer is dried without removing the swelling solvent from the polymer, the dissolved plasticizer may remain inside the recycled polymer, reducing the efficiency of plasticizer removal. Therefore, it is important to remove the swelling solvent from the swollen polymer. According to the present invention, the swollen polymer is shrunk by a chemical method using a shrinkage solvent, thereby minimizing the solvent content and plasticizer content present in the swollen polymer.

[0060] The shrinking solvent is preferably a solvent that does not swell the polymer to a large extent, unlike the swelling solvent. Furthermore, when the additive is a phthalate-based plasticizer, the shrinking solvent is preferably a solvent that dissolves the phthalate-based plasticizer to a large extent. From this perspective, when the additive is a phthalate-based plasticizer, the shrinking solvent may be one or more of ethyl alcohol, toluene, cyclohexanol, isopropyl alcohol, benzene, cyclohexane, 1-pentanol, 1-butanol, 1-propanol, hexane, and diethyl ether, and more specifically, isopropyl alcohol. Such a shrinking solvent not only efficiently shrinks the swollen polymer but also has an excellent ability to dissolve the phthalate-based plasticizer, allowing the plasticizer present inside the polymer to be easily removed to the outside of the polymer during shrinkage of the swollen polymer.

[0061] To facilitate shrinkage of the polymer swollen by the shrinking solvent in the shrinking zone 200 and the smooth removal of the swelling solvent (and additives contained therein) from the swollen polymer, the supply flow rate of the shrinking solvent supplied through the shrinking solvent inlet 50 can be determined based on the supply flow rate of the polymer and the bulk density of the supplied polymer. Specifically, the following general formula 4 can be satisfied:

[0062] [General formula 4] Feed flow rate of the supplied polymer (g / min) / bulk density of the supplied polymer (g / cm 3 )*0.25≦Shrinkage solvent supply flow rate (cm 3 / min) ≦ Supply flow rate of supplied polymer (g / min) / Bulk density of supplied polymer (g / cm 3 )*5

[0063] The residence time of the polymer in the shrinkage zone 200 may be 0.5 to 10 minutes. If the residence time of the polymer in the shrinkage zone 200 is short, i.e., less than 0.5 minutes, the shrinking solvent cannot penetrate deep enough into the polymer, which may result in a slow shrinkage of the swollen polymer and a reduced efficiency of additive removal. If the residence time of the polymer in the shrinkage zone 200 is longer than necessary, it may be uneconomical in terms of the amount of solvent used and the size of the apparatus.

[0064] According to one embodiment of the present invention, the polymer that has passed through the shrinking zone 200 may be discharged to the outside of the additive removal device 1 through the polymer outlet 30. The discharged polymer may be subjected to a drying process to remove the swelling solvent and shrinking solvent remaining in the polymer. The dryer in which the drying process is performed may be, for example, a paddle dryer, a floating bed dryer, a vacuum dryer, or a devolatilizing extruder.

[0065] Meanwhile, according to an embodiment of the present invention, the swelling solvent and the shrinking solvent may be discharged through a solvent discharge portion 60 .

[0066] The solvent discharge unit 60 may be coupled to one end of the barrel 10, and may include a solvent outlet. The solvent discharge unit 60 may be detachable from the one end of the barrel 10 for cleaning the inside of the barrel 10, etc.

[0067] The solvent discharged through the solvent discharge unit 60 may contain a swelling solvent, a shrinking solvent, and additives dissolved therein. Therefore, a purification process may be performed on the discharged solvent to separate the swelling solvent, the shrinking solvent, and the additives, and the resulting solvent and additives may be reused.

[0068] The present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and technical concept of the present invention, and the scope of the present invention is not limited to these examples.

[0069] Examples and Example 1 First, an additive removal apparatus 1 was prepared as shown in Figure 1. Specifically, the additive removal apparatus included a barrel 10 with an inner diameter of 6 cm, a polymer inlet 20 on one side, and a polymer outlet 30 on the other side. A motor 80 was installed at the other end of the barrel, and a screw 70 connected to the motor was installed inside the barrel. The additive removal apparatus also included a swelling solvent inlet 40 and a shrinking solvent inlet 50 between the polymer inlet and the polymer outlet. Here, the ratio x / y of the distance x from the polymer inlet to the swelling solvent inlet and the distance y from the swelling solvent inlet to the shrinking solvent inlet was 4.

[0070] The additive removal device was placed on a support table, and the inclination between the extension of the rotational center axis of the screw and the ground was adjusted to 15 degrees.

[0071] Next, a polymer powder sample containing PVC recycled polymer (D50: 200 μm) containing 14.3 wt% of phthalate plasticizer was prepared, and methyl ethyl ketone (MEK) was used as a swelling solvent and isopropyl alcohol (IPA) was used as a shrinking solvent. Next, MEK was poured into the swelling solvent inlet 40 at a volume of 15.5 cm. 3 10.6 cm of IPA was injected into the shrink solvent inlet 50 at a volumetric flow rate of 10.6 cm / min (0.75 kg / hr in terms of mass flow rate).3 After confirming that the normal state had been reached by supplying the polymer powder sample at a volumetric flow rate of 4.2 g / min (=0.25 kg / hr) to the polymer inlet 20, the polymer powder sample was supplied at a mass flow rate of 4.2 g / min (=0.25 kg / hr). Meanwhile, the screw rotation speed was set to 1 rpm, and the polymer powder sample was passed through the swelling zone 100 and the shrinkage zone 200 in that order, and discharged to the polymer outlet 30. The residence time of the polymer in the swelling zone was 24 minutes, and the residence time in the shrinkage zone was 6 minutes.

[0072] 0.5 g of PVC polymer was sampled from the polymer outlet 30 and analyzed by gas chromatography-flame ionization detection (GC-FID) to calculate the residual phthalate plasticizer content in the sample. The GC-FID analyzer used was an Agilent 7890A GC system. The residual plasticizer content was found to be 100 ppm.

[0073] Example 2 Compared with Example 1, MEK was poured into the swelling solvent inlet 40 at a rate of 7.5 cm. 3 2.7 cm of IPA was injected into the shrink solvent inlet 50 at a volumetric flow rate of 1 / min (0.375 kg / hr in terms of mass flow rate). 3 The plasticizer in the PVC polymer was removed using the same device and method as in Example 1, except that the plasticizer was supplied at a volumetric flow rate of 0.125 kg / min (mass flow rate of 0.125 kg / hr).

[0074] The residual plasticizer concentration of the discharged PVC polymer was measured in the same manner as in Example 1, and was found to be 250 ppm.

[0075] Comparative Example 1 In comparison with Example 1, no solvent was supplied to the swelling solvent inlet 40, and MEK, the swelling solvent, was supplied only to the shrinking solvent inlet 50 at a rate of 25.9 cm 3 The plasticizer in the PVC polymer was removed using the same equipment and method as in Example 1, except that the polymer was supplied at a rate of 1.25 kg / min (mass flow rate of 1.25 kg / hr) and the residence time of the polymer in the equipment was set to 30 minutes.

[0076] The residual plasticizer concentration of the discharged PVC polymer was measured in the same manner as in Example 1, and was found to be 4,200 ppm.

[0077] Comparative Example 2 Compared with Comparative Example 1, 26.5 cm of IPA, which is a shrinking solvent, was injected into the shrinking solvent injection port 50 only. 3 The plasticizer in the PVC polymer was removed using the same device and method as in Comparative Example 1, except that the feed rate was 1.25 kg / min (mass flow rate of 1.25 kg / hr).

[0078] The residual plasticizer concentration of the discharged PVC polymer was measured in the same manner as in Example 1, and was found to be 62,000 ppm.

[0079] Comparative Example 3 In comparison with Comparative Example 1, a mixed solvent of MEK as a swelling solvent and IPA as a shrinking solvent in a weight ratio of 1:1 was poured into the shrinking solvent inlet 50 at 26.0 cm 3 The plasticizer in the PVC polymer was removed using the same device and method as in Comparative Example 1, except that the feed rate was 1.25 kg / min (mass flow rate of 1.25 kg / hr).

[0080] The residual plasticizer concentration of the discharged PVC polymer was measured in the same manner as in Example 1, and was found to be 1,400 ppm.

[0081] From the above results, it was possible to efficiently remove additives from polymers using a continuous method by utilizing the additive removal device of the present invention. Referring to Examples 1 and 2, it was confirmed that high additive removal efficiency could be achieved by introducing a solvent that swells the polymer and a solvent that shrinks the polymer into the swelling solvent inlet and shrinking solvent inlet, respectively, of the additive removal device. However, when only one of the swelling solvent or shrinking solvent was used at the same flow rate (Comparative Examples 1 and 2), or when a mixture of the same solvents was used at the same flow rate, it was difficult to achieve the desired plasticizer removal efficiency (Comparative Example 3).

Claims

1. a barrel providing an interior space and having a polymer inlet on one side and a polymer outlet on the other side; a screw provided in the internal space of the barrel and rotating about its axis; a solvent discharge port provided at the one end of the barrel; A support stand for supporting a polymer outlet, and a support stand for supporting a polymer inlet. Including, the barrel includes a swelling solvent inlet located between the polymer inlet and the polymer outlet and adjacent to the polymer inlet, and a shrinking solvent inlet located between the polymer inlet and the polymer outlet and adjacent to the polymer outlet, The support supporting the polymer outlet is longer than the support supporting the polymer inlet; The inclination between the extension line of the rotation center axis of the screw and the ground is 5 to 30 degrees. Additive removal device.

2. a rotational force supply device is provided at the other end of the barrel; 2. The additive removal device according to claim 1, wherein the screw includes a shaft connected to the torque supply device and rotatable about its axis, and a plate fixed to an outer circumferential surface of the shaft and extending helically along the length of the shaft.

3. 2. The additive removal device according to claim 1, wherein the polymer introduced into the polymer inlet is transported to the polymer outlet by the axial rotation of the screw and discharged.

4. 2. The additive removal device according to claim 1, wherein the internal space of the barrel is divided into a swelling zone from the polymer inlet to the swelling solvent inlet and a shrinking zone from the swelling solvent inlet to the shrinking solvent inlet.

5. 2. The additive removal device according to claim 1, wherein a ratio x / y of a distance x from the polymer inlet to the swelling solvent inlet to a distance y from the swelling solvent inlet to the shrinking solvent inlet is 0.1 to 60.

6. providing an additive removal apparatus according to claim 1; supplying a polymer containing an additive to the polymer inlet, and supplying a swelling solvent and a shrinking solvent to the swelling solvent inlet and the shrinking solvent inlet, respectively; transferring the supplied polymer to a polymer outlet by axial rotation of the screw; Swelling the polymer in a swelling zone from the polymer inlet to the swelling solvent inlet; and shrinking the polymer in a shrink zone from the swelling solvent inlet to the shrink solvent inlet.

7. The method for removing an additive according to claim 6, wherein the additive is one or more phthalate-based plasticizers selected from the group consisting of dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl terephthalate (DOTP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), di-(2-ethylhexyl) terephthalate (DEHTP), and butyl benzyl phthalate (BBP).

8. 7. The method for removing an additive according to claim 6, wherein the polymer is polyvinyl chloride (PVC).

9. The method for removing an additive according to claim 6, wherein the swelling solvent is one or more of cyclohexanone, cyclopentanone, N,N-dimethylacetamide, tetrahydrofuran, pyridine, 3-pentanone, 2-pentanone, dimethylformamide, methyl ethyl ketone, dichloromethane, 4-methylpentan-2-one, nitrobenzene, 1,4-dioxane, 1,1,2,2-tetrachloroethane, acetone, ethyl acetate, chloroform, and dimethyl sulfoxide.

10. 7. The method for removing an additive according to claim 6, wherein the shrinking solvent is one or more of ethyl alcohol, toluene, cyclohexanol, isopropyl alcohol, benzene, cyclohexane, 1-pentanol, 1-butanol, 1-propanol, hexane, and diethyl ether.

11. The method for removing an additive according to claim 6, wherein the residence time of the polymer in the swelling zone and the average particle size (D50) of the polymer satisfy the following general formula 3: [General formula 3] Average particle size of polymer (mm) * 5 ≦ Residence time in swelling zone (min) ≦ Average particle size of polymer (mm) * 240

12. 7. The method for removing an additive according to claim 6, wherein a flow rate ratio of the flow rate of the shrinking solvent supplied to the shrinking solvent inlet to the flow rate of the swelling solvent supplied to the swelling solvent inlet is 30% by volume to 300% by volume.

13. 7. The method for removing an additive according to claim 6, wherein the residence time of the polymer in the shrinkage zone is 0.5 to 10 minutes.

14. The method for removing an additive according to claim 6, wherein the supplied swelling solvent and shrinking solvent are transported to a solvent discharge section by gravity and discharged.

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